1. Field of the Invention
This invention relates to Doppler motion detection with automatic angle correction and, in particular, to the calculation and display methods of Doppler angles. This method utilizes efficient correlation processing to compute the angle of motion and is applicable to real-time two-dimensional imaging. Using a two-dimensional mapping table, the method can be realized in current imaging systems.
2. Description of the Prior Art
Doppler effect is used to detect the velocity of motion from the frequency shift caused by the relative motion between two objects. In medical ultrasonic imaging, it is also widely used to compute the velocity of the blood flow or myocardial motion in human bodies, so it provides very important information for clinical diagnosis. However, the velocity measured by this method is the projection of the actual velocity onto the propagation direction of the sound waves. There will be no way to measure the real velocity and perform quantitative analysis without proper angle correction. To resolve this problem, current commercial systems rely on the operator to make the correction by marking the projection angle of the vessel displayed in the B-mode image. The main drawbacks of this type of methods are inconvenience and potential human errors. In contrast to the manual marking method, automatic measurement of Doppler angles has been proposed by various research groups. Although the basic principles of these methods are different, yet they all involve complicated calculations or need to significantly modify current system architectures. The present invention provides improvements over the previous methods.